Design and calculation of a 130 kW high-speed permanent magnet synchronous machine in flywheel energy storage systems for urban railway application

摘要

The design of high-speed electrical machines for flywheel systems should consider simultaneously electromagnetic, mechanical and thermal constraints. This paper presents the design of a 4-pole permanent magnet synchronous machine (PMSM) for a flywheel energy storage system, which is applied in an urban railway system. The machine has a maximum speed of 24000 min and a rated power of 130 kW. A design criterion for the PMSM with surface mounted magnets is put forward in this paper to determine the air gap flux density and the magnet thickness by taking mechanical strength limit and the risk of demagnetization into account. The mechanical strength limit is determined based on the optimization of the bandage thickness for given constraints. The mechanical performance and demagnetization behavior are validated by a FEM simulation. The thermal behavior is evaluated with a lumped parameter thermal model. Additionally, the machine is designed to be short circuit tolerant for safety concerns. Therefore, the short circuit behavior of the machine is analyzed for various speeds. The calculation results validate the feasibility of the proposed design, with a calculated average efficiency of 97.2 % for the defined two operating points.